soderberg



Lian. 2, 1923. 1,441,037.

a C. W. SODERBERG.

PROCES 0F BAKING CARBON ELECTRODES.

FILED uc.4.19n. -2 suzns-suzn mm! W Inventor, Carl Wilhelm SbderbQrg y MAttorneys 2 SHEEIS-SHEEI 2.

C. W. SODERBERG.

PROCESS OF BAKING CARBON ELECTRODES.

' FILED DEC.4. I917.

Jan. 2, 1923.

Inventor,

Car] Wilhelm Siderberg 13 $@&

W Attorneys Patented Jan. 2, 1923.

um'ranwsra'ras PATENT OFFICE.

CARL WILHELM sonnRBERG, or 'CHRISTIANIA, NORWAY, ASSIGNQR 'ro DIETNORSKE AKTIESELSKAB son ELEKTROKEMISK nmrrs'rm or NORWAY. orcnm's'rmnra,

NORWAY.

P3061385 OF BAKING CARBON ELECTRODES.

Application-filed December4, 1917. Serial No. 205,416.

To all whom it may concern:

Be it known that I, CARL Wimmmr 860cm BERG, a subject of Norway, and' aresident of Christiania, Kingdom of Norway, have 5 invented certain ;newand, useful Improve-z ments in the Processesof BakingCarbon Electrodes,of which the followings a speci is an improved; process formanufacturing the same and the electrode obtained there-.

by, V i

Electrodes for the. purpose abore mentioned are generally made from somecarbonaceous material such as coal, coke, graphite, etc. -The materialor materials select-, ed are reduced to the. desired fineness and mixedwith a. suitable binder such as;tar.or pitch. The mixture is thenmoulded to the desired form and baked in a suitable furnace until thevolatile products are driven off and the electrode has the desireddensity,

and conductivity.

,The raw. electrodes have a com aratively high resistance and are notcon uctive to any appreciable extent. The resistance,

however depends somewhat upon the materials employed in the manufacture;for instance, an electrode of course graphite will have a higherconductivity, than-one composed of other carbonaceous materials. In

most cases the raw electrode will have a conductivity about 10000 timeslower than it will have in the finished state.

Many attempts have been made to bake electrodes by means of the heatgenerated within the electrode itself when made a part of an electriccircuit. but on account of the high resistance of the raw electrodes,this method has been found to be impractical.

According to my invention thisdiiiiculty is overcome by baking andrendering the electrode conductive in a part of its cross-section bymeans of heat electrically generated in a conductor connected inparallel with the electrode. This conductor may consist of metal or of abaked electrode. Preferably it is one or more iron bars inserted in" theelectrode itself.

As will be understood from the following examples my method issusceptible ofmany variationsall of which embody theprocess aboveoutlined. For instance, electrodes may be baked in a special electricfurnace or thebaking may be carried on simultaneously with the use oftheelectrode itselfin the furnace in whichit is mounted. In the.lat tercase a portion of the baking is accent-.1 plished by the heat of thefurnace ingwhich the. electrode is employed.

In either of the instances citcd' -the electrode may be of the same.construction and made in the samemanner. A -mould maybe employed inthisprocess: in which is preferably mounted. a core of. conductiye material,such as a rod ofironindiameter,

for example. 1}". or a small carbonaceous electrode. The raw materialsfor-the elec trode are tamped around the core in the. usual manner andthe mould removed-as,

15 e e-1 ployed for the baking of the electrode, the,

will bereadily understood. here a, separate furnace isv to rawelectrodes are placed therein and are series-connected in thesecondaryof a trans,-v former furnishing sufiicient current for thebaking. With twenty electrodes, for example, a 400 kilowatt transformerof the voltage regulator type 'ving from. 220 to 110 volts may be used.0 this end electrode No. 1 may be placed on a carbon-block, that isconnected to one terminal of the secondary. On the top-end of the sameelectrodeis. placed a. short piece of carbon or graphite ,electrode ofgood conductivity, that will; take the current over to the top-end ofelectrode. No. 2. The lower end of No. 2 rests on another piece of acarbon or graphite electrode. Electrode No. 3 is placed, on the samepiece of carbon or graphite. and so on, the last electrode of the seriesbeing connected to the other terminal of the. secondary. The spacesbetween the electrodes are then filled with fine sand or finely groundcharcoal.

If the current is switched on with about 200 volts between theterminals, the ameter will immediately register about 800 amperes Thecurrent drops slightly at the start and then gradually rises to. about2500 to 3000 amperes during a period of 24 to 36 hours as the baking ofthe electrodes proceeds. At the end of this time the baking is finishedand the drop of potential will be about 6.

volts per electrode if thecurrent is 3000mm ]:t'|(:-. l: is p s ible touse a transformer without voltage regulation, but thepbaking will thenproceed more slowly.-

The electrodes baked as above are allowed to cool before removing fromthe furnace. This requires about 36 hours. v

if an iron core has been employed its presence in the finished electrodev0u'ld7depend on the temperature obtained during baking. if it is dsiredto bakeatfrbhi 'lfiflfl" to 1600" C. t-h e iron will obviously melt andthe baked poi tiOn alone of the -electrode carry the current to complete'thefiiaking. Generally so high temperatures are not necessaryand'the'iron-rod will'be found in the electrode after the baking. 7 I

As a variation 'in the above method of baking in a separate furnace, itis readily possible if desired to make use of baked electrodes in placeof an interior core. In that case the following.arrangementsofelectrodes will be employed",

Thera'w electrodes and'thc ready baked electrodes arebiiilt-"ilpfioget-her,,'always one raw and one'bakedelectrode closetogether and with top "and bottom' connected to the same conductor. Atfirst the current will slightly conductivl'and takes part in the"transmission of current." The 'conduct ivity and the resultmg'lfeiitde'relopment increase until the raw electrode is'fihallv hiiked. The'secpndniethod 'ofibakirii electrodes. f

to wit; by the useof the fu'rr iiiceiin which particularlyadyantageoiiswher very long electrodes ar''dsired, though obviously not limited thereto'l fThe present type of electrode is about six feet long and toemploy. tl1ese.in'-the"fui naces referred to requircs their being joinedtogether and the present practice is to use a "fragile carboiinippleforthis purpose. Tlie .metlibd now to be con sidered not onl eliminatesthis difiicultyliut. in makinig nse of theclectric furnaceitself. forbaking makes possible" the continuous supply o fele ctrodes \vithoutshnltir rc down the furnace for'theinstallaliou of new (l.r trodes. d

This method is shonn (liagrauunatirallv in the drawings which form apart hereof and which itisdofhc understood. arc for illustrativepurposes onl In these drawings i Figure l isa diagranunatir verticalsect ion of. a simple electric shaft {IH'HIKQ for the manufacture ofpig-iron: and

Fig. 2 is a diagrammatic (1'()S. ':i(llltil1 of the usual type ofmetallurgical furnace.

The figures illustrate not only the diflvr cut t pes of furnace to whichtheproccssis applicable but different methods of baking the electrodesthemselves. 1 V i i aii danthiacite used for making-the electrodc isfilled in the funnel l and tamped around one or moreiron bars 2. Thecurrent is lcd to the furnace through one or more of thcsr -iron barswhich may also serve as a. suspending means for the electrode. The ironha rs may be corrugated or provided with small sliding on them.

As the raw electrode mass is a poor conductor, the' iro n bars initiallywill alone carry the whole current above the shaft and knots in order toprevent the electrode from in the upper and cool part of the shaft.

Through the heat electrically generated in the bars and the h eat'fromthe [smelting crucible the eleet'rode'is gradually baked and becomesconductive and will take part in the transmission of the current. Stillnearer the zone of fusion-as at 3the temperature of the electrode is sohigh. that the iron core melts out, the newly baked carbon electrodealone carrying the current.

The metalusedfor reinforcing the electrode. need not be ironj, An metalcan he used that has 'zi melting: point sumcientlv high above thetemperature at which'the electrode mass becomeswgood conductor. andwhich has snfiic-ient mechanical strength. The reinforcing metal canthus be chosen according to the smelting process in question. they 'areemployed'is heatihgelementspis In the example just dcscribedi the'entire smelting current vas'initihllj led to the'funv na ce throughtheiron core and the cross-seetion of.the -coremustdbefet'ore be largeenough to carry the whole current. It is also possibleto bake'theelectrode. br'a current that is onlyaffraction of the cnrrent used forthe smelting operation. in this case the crossfsection of thc. iron-barscan b(' much smaller. "Fig. 2 illustrates the. cm; ployment of such "amethod by the use of :1 separate transformer. l n this figure theportion 4 of the electrod uscd'fnr smelling is diagrammaticallyillustrated as already having been baked and as suspended from (heelectrode-ho dcr 3 through which it is supplied with the working currentfor e.\' ample. IRON!) arupcres. from the sci-oudary 1 of the l wertranstnrlurr. The upper (1! ranportion of the clcclrode'T formed by lampin;' the raw material ar und the iro lmrg as is readily understood. isconnected in s rics with the secondary R of the upper ll 'lllF formerand snppliz-tl villi a. linking r-urrcnl ull cicnl to ause slow baking;lol' cvnzzplu. about 2000 ampercs. This transformer is preferably of'lowvoltage and potential regulating type. As the lower portion 4. of theelectrode is burned away; the electrode holderfi is shifted to thenewiyimked por tion 7 of the electrode which is then used in thesmelting operation.

The foregoing detailed description has been given for clear'hess ofunderstanding and no undue limitation should be deduced therefrom, butthe appended-'c'iaitns should be commied asbroadl' asf 'eiinissible' inview of the prior art;

hat I claim as" a'ttd' desire to secure by Letters Patent fthe UnitedStates is:-

1. The mcessmFbakingcarbOn electrodes which consists inconnecting'a'conductor in parallel wit-lra-raw' lectrcde and applying anelectric curreht whereby a-=-part ofthe raw electrode'is'baked andrendered conductive by heat electrically generated conductor an'd theJof heacelectrically generated in conductor andin the electrode itself.

2; Therocess off-"baking electhe pp ying-auelectric current ,vmereay apart the conductor" and the-'bakiiigcontinuedby meansofheatlectr'tcallyg'eneratd in the conductor'end in-theeb'trode itself;said conductor being incorporated'with the raw electibde. V p

3. The process" of baking carbon elec trodes" which consists iiro'nflectihg ametal conductor in: parallel with a raw electrode andapplying ah electric current whereby a part of the rawelectrodeEis-baked and rendered conductive by heat electricallygenerated in the metal conductor and the baking continued by means ofheat electrically generatgd in the conductor and in the electrode itsel4. The process of baking carbon electrodes which consists in connectinga metal conductor in parallel with a raw electrode and applying anelectric current whereby a part of the raw electrode is baked andrendered conductive by heat electrically enerated in the metal conductorand the aking continued by means of heat electrically generated in themetal conductor and in the electrodc itself. said metal conductor beingincorporated with the raw electrode.

5. The process of baking carbon electrodes which consists in connectingan iron conductor in parallel with a raw electrode and applying anelectric current whereby a partof th raw electrode is baked and renderedconductive by heat electrically generated in the iron conductor and thebaking continued by means of heat, electrically generated in the ironconductor and in the elect rode itself.

(5. The process of baking carbon-"elm-- trodes which consists inconnecting an iron conductor in parallel with a raw electrode andapplying an electric current whereby a in I the biking" continued bv'part (ff the raw electrode is dered conductive by heat 0 era ted in theiron conductor continued trode itself.-

' means of erated 1n the iron con d baked and roll lcctricn ll genandthe baking;

heat electrically gem uctor and in the elecsald iron conductor beingincorpora'ted with the raw electrode.

(. The

process of baking carbon electrodes which consists in connecting aconductor in pp y conductive by the conductor and rendered heatelectrically generated in and the which is baked tsimultaneousl 8. Theprocess-of. co wasting:away of an -e trode'at-iits 0 which comprlsesadding raw rial to theoppositeend of th baking said 'ra thereto.

9..'I-he process 0 wastin away bakin means of heat electricallyconductor and i conductor and electrode serieswith another; cond ocontinued in generated in the n'the electrode itself. said uctor andelectrode,

mpensating for the lectric furnace elecperatin'g end-within a furnace.

electrode matee electrode and w material afterits addition fcompensating for the of an electric furnace electrode at its operatingend within a furnace. which comprises-adding raw rial to its oppositematerial paitlly rent through-t 1e heat generated :1

end and b electrode an electrode when in use.

10. The process of trodes continuousl produci electrode man-- akingSilltl raw by passing an electric curd partly by the t the operating endof the.

ng carbon eleu y in the furnace in which they are employed, whichcomprises supplymg in electrode form raw together with nection therewithwhereby the r dered conduct electrode material a conductor in parallelconaw electrode is we in and applying current baked and rcnpart by theheat electrically generated in the electrode itself and in part by theheat generated a end of the electrode when in t the opcral in; use.

6 process of baking carbon clec trodes for electric furnaces whichconsists in connecting a raw electrode rent whereby baked and renderedconductor in l and a )arallcl with a pplyin; :in electric cur a part ofthe raw electrode is conducti trically generated in the conductor and[lie baking continued by means cally generate electrode itself. saidelect-rod d in the condu trode of an electric furnace.

12. The

of heat electricto i and in the e being the clc process of bakingrarlion clcrtrodes for electric furnaces which onsists in connecting rawelectrode rent whereby baked and ren trically gencr baking contin aconductor in and applying; a part of the l ated in the con ued by meansparallel with :I an electric (:uraw electrode is dered conductive byheat elecductor and the of heat electriill! vullv generated in tln-vconductor and in the rent whereby a part of the raw electrode is bakedand rendered conductive by heat electrically generated in the conductorand the baking continued by means of heat electrically generated in theconductor and in the electrode itself. said electrode being theelectrode of an electric furnace, the electrode being continuouslyformed in said furnace.

14. The process of balcing carbon elec trodes for electric furnaceswhich consistsin connecting a conductor in parallel with a raw electrodeand applying an electric cur' rent whereby'a part of the raw electrodeis baked and rendered conductive by heat electrically generated inthe-conductor and the baking continued by means of heat electricallygenerated in the conductor and in the electrode itself, said electrodebeing the elm? trode of an electric furnace. and said conductor beingable to carry the total electric current led to the electric furnace.

15. The process of baking carbon electrodes for electric furnaces whichconsists in connecting a conductor in parallel with a raw electrode andapplying an electric current whereby a part of the raw electrode isbaked and rendered conductive by heat electrically generated in theconductor and the baking continued by means of heat eler tricallygenerated in the conductor and in the electrode itself, said electrodebeing the electrode of an electric furnace, and said conductor beingable to carry only part of the total electric current led to thefurnace.

16. As a new and useful article of manu- 18. As a new and useful articleof menufacture, an electrode baked in the furnace in whichit is used andcomprising when in use a baked vportion and'a partially baked porti0n.

19. As a new and useful article of manufacture, an electrode baked inthe furnace in which it is used and comprising when in use a bodyportion, a part of which is baked and a part'of which is unbaked, and areinforcing member of conductive material in parallel electricalrelation therewith.

20. As a new and useful article of manufacture, an electrode for use inan electric furnace comprising a body portion structurally differing atits two ends and a rein forcing member of conductive material inparallel relation therewith, the c0nductivity of the body portion beingpermanentlv greater at the working end thereof.

CARL WILHELM SGDERBERG.

